Pseudostratified Columnar Epithelium

At a glance

Single layer where all cells touch basement membrane but nuclei stagger at different heights, giving a stratified look.
Classic in respiratory tract with cilia and goblet cells; also in male reproductive tract (non-ciliated with stereocilia).
Basal cell population is the regenerative engine; cilia/secretory mix signals function.
Markers: CK7/CK8/18+, basal p63/CK5/6+, FOXJ1 for ciliated cells, SCGB1A1 for club cells, androgen receptor in epididymis/vas.

Large Intrapulmonary Bronchi

1. Architecture

Same basic pseudostratified pattern as trachea but usually a bit thinner.

Why: as airways branch, airflow is lower and the mucosa can be slightly less robust.

Ciliated cells, goblet cells, basal cells, plus Clara or club type cells appearing more distally.

Why: deeper airways need detox and surfactant like functions.

Sits on basement membrane over a lamina propria with more smooth muscle and less cartilage than trachea.

Why: bronchi must regulate caliber more actively.

2. Cytologic Features

Ciliated columnar cells still predominant.

Why: mucociliary clearance is still required.

Goblet cell number can be lower than in trachea.

Why: less particulate load deeper in the tree.

Basal cells present at the base.

Why: maintain regeneration.

3. Polarity and Attachment

Apical tight junctions.

Why: protects underlying connective tissue from inhaled material.

Desmosomes laterally.

Why: bronchi open and close with breathing and coughing.

4. Basement Membrane

Continuous BM, thickness can vary by site and by chronic inflammation.

Why: still the scaffold for repair.

5. Functional Correlation

Main job is still clearance plus early conditioning of air.

Why: large bronchi are still conducting, not exchange.

More club like cells distally help with detox.

Why: deeper parts need local protective secretions.

6. Regeneration and Injury

Viral bronchitis and asthma can denude ciliated cells.

Why: cilia are the most exposed.

Basal cells and surviving columnar cells re-epithelialize the surface.

Why: one BM makes sliding repair easy.

7. Biomarkers

Epithelial: pan CK+, CK7+, CK8/18+.
Basal layer: p63+, CK5/6+.
Ciliated: FOXJ1+.
Goblet: MUC5AC+.
Club cells: can express SCGB1A1 (if you ever need to document them).

Why: pattern is similar to trachea but with occasional club cell markers.
Negative: endothelial and hematolymphoid markers.

8. Typical Anatomic Correlate

Segmental and lobar bronchi inside the lung.

Nasal Cavity and Nasopharynx

1. Architecture

Pseudostratified ciliated columnar, often with many goblet cells and sometimes with patches of specialized olfactory epithelium more superiorly.

Why: nasal air is cold, dry, and dirty, so more mucus is needed.

All cells reach the BM, not all reach the lumen.

Why: keeps one repair layer.

Mixed mucous and serous glands in the lamina propria.

Why: to humidify and clean the incoming air.

2. Cytologic Features

Ciliated cells forming the mucociliary blanket.

Why: moves mucus toward pharynx.

Abundant goblet cells.

Why: nasal air has a high particulate and allergen load.

Basal cells along BM.

Why: needed for chronic low grade injury.

3. Polarity and Attachment

Apical tight junctions.

Why: sinonasal mucosa is exposed to pathogens and allergens.

Desmosomes laterally.

Why: sneezing and airflow stress the surface.

4. Basement Membrane

Continuous BM, can appear thickened in chronic rhinitis or allergy.

Why: chronic inflammation stimulates subepithelial collagen.

5. Functional Correlation

Primary role is air conditioning.

Why: cilia and mucus trap particles, glands humidify, vascular plexus warms the air.

Also immunologic interface.

Why: close to lymphoid tissue of nasopharynx.

6. Regeneration and Injury

Infection or allergy can cause goblet cell hyperplasia and loss of cilia.

Why: epithelium tries to protect itself, but at the cost of clearance.

Chronic irritation can lead to metaplasia to stratified squamous in vestibular or more exposed zones.

Why: vestibule needs tougher cover.

7. Biomarkers

Epithelial: pan CK+, CK7+, CK8/18+, EMA+.
Basal: p63+, CK5/6+.
Ciliated: FOXJ1+.
Goblet: MUC5AC+.
If olfactory areas are sampled, they show a different neuronal profile (OMP, sustentacular markers) which helps separate them from standard respiratory mucosa.
Negative: CD31, CD45 for the lining.

8. Typical Anatomic Correlate

Inferior and middle nasal cavity, parts of paranasal sinuses, nasopharyngeal respiratory surface.

Stereocilia of Epididymis and Proximal Ductus Deferens

(This one looks like it has cilia but they are long, irregular, non motile. They are actin based, so more like very long microvilli.)

1. Architecture

Pseudostratified epithelium with very tall principal cells and long stereocilia plus a basal cell layer.

Why: epididymis needs a very large apical surface to modify and reabsorb fluid around sperm.

All cells touch the basement membrane, not all reach the lumen.

Why: maintains a single regenerative layer.

Lamina propria thin and vascular.

Why: close contact with and control over luminal contents.

2. Cytologic Features

Principal cells very tall, with elongated nuclei and apical stereocilia forming a shaggy border.

Why: stereocilia increase surface area for absorption and secretion.

Basal cells small, near BM.

Why: stem cells for regeneration.

No true motile cilia.

Why: sperm is not moved by ciliary beating here, but by peristalsis in the duct and by fluid changes.

3. Polarity and Attachment

Apical membrane has stereocilia supported by actin.

Why: long term absorption without active beating.

Tight junctions near apical part of tall cells.

Why: epididymal lumen composition must be precisely controlled to mature sperm.

Desmosomes laterally.

Why: prevents epithelium from splitting when duct contracts.

4. Basement Membrane

Single, continuous BM.

Why: provides the scaffold for a very orderly epithelium.

5. Functional Correlation

Main role is fluid resorption, secretion of epididymal factors, and sperm maturation.

Why: sperm leaving the testis is not ready yet.

Large apical surface helps concentrate sperm.

Why: fluid has to be removed efficiently.

6. Regeneration and Injury

Can regenerate from basal cells after obstruction or inflammation.

Why: the BM is preserved so cells can repopulate.

7. Biomarkers

Epithelial: pan CK+, CK7+.

Why: confirms epithelial lining.
Androgen receptor (AR)+ in principal cells.

Why: epididymal function is androgen dependent.
Stereocilia: actin positive, not tubulin based.

Why: distinguishes them from respiratory cilia.
Negative: respiratory ciliary marker FOXJ1.

Why: proves these are not motile cilia.
Negative: PSA and PAP (those are prostate).

Why: helps in male tract lesions.

8. Typical Anatomic Correlate

Epididymis (head, body, tail) and proximal ductus deferens.

Trachea and Main Bronchi

1. Architecture

Pseudostratified epithelium with cilia and goblet cells.

Why: airway must both trap particles and move them up, so it needs mucus makers and movers in the same lining.

All cells touch the basement membrane but not all reach the lumen.

Why: this keeps one regenerative plane while allowing cells of different heights.

Cell types present: ciliated columnar cells, goblet cells, basal cells, small secretory/brush cells.

Why: this mix provides barrier, clearance, and repair.

Rests on a thick basement membrane over loose lamina propria rich in vessels and seromucous glands.

Why: good blood flow warms inspired air and feeds a metabolically active mucosa.

2. Cytologic Features

Ciliated cells with apical ciliary tuft.

Why: cilia beat upward to clear mucus toward the pharynx.

Goblet cells with pale mucin droplets.

Why: make the sticky layer that captures dust and microbes.

Basal cells small, dark, triangular, attached to BM.

Why: they are the stem/progenitor pool.

Nuclei at different heights.

Why: gives the typical pseudo layered look.

3. Polarity and Attachment

Apical pole faces moving air and mucus.

Why: all defensive specializations must be here.

Tight junctions at the top of tall cells.

Why: prevents leakage of airway surface fluid and allergens between cells.

Desmosomes laterally.

Why: coughing, speaking and airflow pull on the surface, so lateral adhesion must be strong.

4. Basement Membrane

Thick, often hyalinized basement membrane, especially in chronic asthma.

Why: repeated inflammation stimulates subepithelial collagen deposition that makes the BM look thickened.

5. Functional Correlation

Mucociliary clearance is the main function.

Why: captures particles low in the tract, then moves them up to be swallowed.

Also conditions inspired air by keeping a moist surface.

Why: trachea is the first large intrathoracic airway and must protect distal bronchioles.

6. Regeneration and Injury

Basal cells proliferate and replace ciliated and goblet cells.

Why: rapid turnover is needed after viral infection or smoke injury.

Chronic smoke or severe irritation can cause squamous metaplasia.

Why: surface trades cilia and mucus for a tougher squamous cover.

7. Biomarkers

Epithelial: pan CK (AE1/AE3)+, CK7+, CK8/18+, EMA+.

Why: confirms mucosal epithelial nature.
Basal cells: p63+, p40+, CK5/6+.

Why: identifies the reserve layer.
Ciliated cells: FOXJ1+, beta tubulin IV+.

Why: proves true motile cilia.
Goblet cells: MUC5AC+, MUC1+.

Why: typical airway mucin profile.
Sometimes: TTF 1 weak to moderate, depending on level and lab.

Why: supports respiratory differentiation.
Negative: CD45, CD31, ERG, S100.

Why: rules out lymphoid, vascular, neural.

8. Typical Anatomic Correlate

Trachea and right and left main bronchi.

Ciliated

Trachea and Main Bronchi

Large Intrapulmonary Bronchi

Nasal Cavity and Nasopharynx

Stereocilia of Epididymis and Proximal Ductus Deferens

Generalities

1. Architecture

Appears multilayered, but every cell sits on the basement membrane.

Why: basal and intermediate cells are short and stay low, tall cells reach the lumen, so nuclei are at different heights and the epithelium looks stratified even though it is not.

Tall columnar cells reach the lumen and are usually ciliated.

Why: these are the working cells that move mucus and trap particles.

Basal (reserve) cells are small, triangular, at the base.

Why: they act as stem/progenitor cells and keep the epithelium attached.

Goblet cells interspersed.

Why: airway needs a mucous blanket to trap dust and microbes.

Single continuous basement membrane.

Why: even if cells are different heights, the epithelium must regenerate along one plane.

2. Cytologic Features

Ciliated columnar cells with apical ciliary border.

Why: cilia beat to move the mucus layer toward the pharynx.

Goblet cells with pale/foamy cytoplasm.

Why: they store mucin droplets to release onto the surface.

Basal cells with darker, round nuclei near the basement membrane.

Why: small size makes room above for taller functional cells.

Nuclei at several levels.

Why: mixed cell heights create the pseudo-stratified look.

3. Polarity and Attachment

Apical pole faces the airway lumen.

Why: this is where cilia beat and where mucus is released.

Lateral borders joined by junctional complexes, especially near the lumen.

Why: prevents mucus and surface fluid from leaking between cells.

Basal surface on basement membrane with hemidesmosomes.

Why: air movement causes shear so the whole sheet must stay fixed.

4. Junctional Complexes

Tight (occluding) junctions near apical portion of the tall cells.

Why: keeps the mucous layer on top and prevents paracellular leak of irritants.

Adherens junctions (E-cadherin, catenins) linking to actin.

Why: holds neighboring cells together during coughing and deep breathing.

Desmosomes between lateral surfaces.

Why: extra spot strength for repeated mechanical stress.

Gap junctions between some cells.

Why: allows coordination of ciliary activity and repair signals.

5. Basement Membrane

Thick, continuous basement membrane, often conspicuous in chronic asthma.

Why: chronic irritation stimulates subepithelial collagen so the BM looks thicker but still serves as the repair scaffold.

Composed of type IV collagen, laminin, proteoglycans.

Why: classic epithelial attachment mix for ciliated mucosa.

6. Cytoskeleton and Apical Specializations

Apical cilia with 9+2 axoneme and basal bodies.

Why: true motile cilia are needed to move mucus proximally.

Actin network in apical cortex.

Why: stabilizes the apical domain that carries cilia.

Intermediate filaments: epithelial cytokeratins (CK8/18/19) plus basal keratins in basal cells.

Why: gives tensile strength and identifies the lining as epithelial.

7. Immunohistochemistry

Epithelial core: pan-cytokeratin (AE1/AE3)+, CK7+, CK8/18+, EMA+.

Why: confirms respiratory epithelial nature.

Basal cells: p63+, often p40+, CK5/6+.

Why: shows the stem/progenitor compartment at the base.

Ciliated cells: FOXJ1+ (transcription factor for motile cilia).

Why: proves true ciliary differentiation.

Goblet cells / mucous cells: MUC1+, MUC5AC+.

Why: identifies secretory/mucous phenotype of airway.

Sometimes: TTF-1 positive in more proximal airway/respiratory differentiation, depending on level and fixation.

Why: helps separate primary lung/airway lining from metastasis.

Negative: CD45, CD31/ERG, S100.

Why: rules out inflammatory, vascular, and neural components.

8. Vascularity and Nutrition

Epithelium itself is avascular.

Why: ciliated mucosa needs to stay smooth and thin.

Supplied by underlying vascular lamina propria.

Why: diffusion from below is enough for this thickness.

9. Functional Correlation

Primary function: mucociliary clearance.

Why: goblet cells make mucus to trap particles and cilia move that mucus toward the pharynx.

Secondary function: barrier against inspired air, microbes, and pollutants.

Why: tight junctions and mucus together prevent direct contact with the lamina propria.

Reserve/progenitor function in basal cells.

Why: airway lining is often injured (smoke, infection) and must regenerate quickly.

10. Regeneration and Injury

Basal cells proliferate and differentiate upward.

Why: maintains the height differences that define pseudostratified epithelium.

Chronic irritation (smoking, pollution) can cause goblet cell hyperplasia.

Why: body tries to make more mucus to protect itself.

Severe or chronic injury can cause squamous metaplasia.

Why: if the environment is too harsh, the airway sacrifices cilia and mucus and switches to tougher stratified squamous.

11. Typical Anatomic Correlates

Trachea and primary bronchi.

Why: these are high-flow, high-particle airways that must clean incoming air.

Large intrapulmonary bronchi.

Why: still need mucociliary clearance.

Nasal cavity and nasopharynx (respiratory parts).

Why: exposed to dry, cold, and dirty air so cilia and mucus are needed.

Main Variants You Will See

A. Pseudostratified Columnar with Stereocilia (Epididymis)

Architecture: basal cells + very tall principal cells with long, non-motile stereocilia.
Why: increases apical surface to reabsorb and mature sperm, not to move mucus.
Biomarkers: pan-CK+, AR+, ERG negative, PSA/PAP negative (not prostate). Actin in the stereocilia.
Function: fluid modification and sperm storage.

B. Pseudostratified in Proximal Male Urethra / Ejaculatory Ducts

Architecture: similar staggering of nuclei, fewer cilia, sometimes secretory.
Biomarkers: pan-CK+, CK7+, EMA+, sometimes AR+.
Function: protect and lubricate a lumen with variable flow.

Body (Corpus)

1. Architecture

Pseudostratified columnar epithelium, still with stereocilia but usually slightly shorter than in the head.

Why: resorption continues but secretory and maturation roles increase, so extreme height is less critical.

Basal cells on the same basement membrane.

Why: maintains single repair plane.

2. Cytologic Features

Principal cells columnar, not quite as tall, stereocilia still obvious.

Why: balance between absorption and secretion.

Basal cells small, at the base.

Why: renewal compartment.

3. Polarity and Junctions

Tight junctions remain well developed.

Why: luminal composition is still important for sperm maturation.

Desmosomes between principal cells.

Why: duct still contracts.

4. Basement Membrane

Continuous BM, sometimes slightly thicker with age or inflammation.

Why: provides a track for repair.

5. Functional Correlation

Continues fluid resorption but shifts toward secretion of epididymal glycoproteins that coat sperm.

Why: sperm gain motility and fertilizing capacity progressively along the epididymis.

Helps create an antimicrobial, stable environment.

Why: protects sperm during storage and transit.

6. Regeneration and Injury

Epididymitis can damage the epithelium but basal cells and preserved BM allow re-epithelialization.

Why: same principle as other pseudostratified epithelia.

7. Biomarkers

Epithelial: pan CK+, CK7+.
AR positive.

Why: androgen still controls protein secretion.
Actin positive stereocilia, FOXJ1 negative.

Why: confirms non motile projections.
May show epididymal specific secretory proteins on specialised panels.
Negative for prostate markers.

8. Anatomic Note

Middle segment of epididymis that is often the longest part.

Efferent Ductules (testis → epididymis) CILIATED EXCEPTION IN EPIDIDYMIS

1. Architecture

Epithelium is not uniform: it is a tall, ciliated, irregular simple-to-pseudostratified epithelium with alternating tall and short cells.

Why: this segment must both move sperm (needs cilia) and remove a lot of fluid (needs absorptive cells), so it alternates cell types.

Many cells reach the lumen, some are shorter, all sit on one basement membrane.

Why: single regenerative plane, variable height for different jobs.

Lumen often looks scalloped or festooned.

Why: the alternating tall/short cells make the edge wavy.

Surrounded by a thin muscular/contractile layer.

Why: helps propel sperm toward the epididymis.

2. Cytologic Features

Tall ciliated cells with true motile cilia (9+2).

Why: they provide active stirring and forward movement of the testicular fluid with sperm.

Short non ciliated (or microvillus) cells, often with endocytic vacuoles.

Why: these are the main fluid resorbers; the testis sends way too much fluid and it must be reduced here.

Basal cells small and near the BM.

Why: reserve/repair population.

Cytoplasm can be pale to eosinophilic depending on activity.

Why: high transport activity changes organelle content.

3. Polarity and Junctions

Apical cilia on the tall cells.

Why: provide active movement, unlike epididymal stereocilia.

Tight junctions apically between neighboring cells.

Why: luminal composition is specialized and must not leak back.

Desmosomes laterally.

Why: ductules contract and would otherwise tear the epithelium.

4. Basement Membrane

Continuous basement membrane.

Why: needed for orderly replacement of these different cell types.

Relatively thin compared with epididymis.

Why: this is a transition, not a storage tube.

5. Functional Correlation

Main job: massive fluid resorption from testicular output.

Why: sperm would be too dilute and would flood the epididymis if this step did not happen.

Secondary job: gentle propulsion/stirring of sperm toward epididymis.

Why: cilia help move the reduced-volume fluid forward.

Combination of ciliated + absorptive cells is the key identifying feature.

Why: epididymis has long non motile stereocilia instead; efferent ductules have true motile cilia.

6. Regeneration and Injury

Inflammation (post orchitis, post vasectomy back-pressure) can flatten the epithelium.

Why: injury makes the lining simplify.

As long as BM and basal cells remain, re-epithelialization is possible.

Why: single BM = single repair track.

7. Biomarkers

Epithelial: pan CK (AE1/AE3)+, CK7+.

Why: confirms ductal epithelial nature.
Ciliated cells: FOXJ1+, acetylated tubulin+.

Why: proves true motile cilia (not epididymal stereocilia).
Absorptive cells: may show endocytic/lysosomal markers on special studies.

Why: reflects fluid uptake role.
Androgen receptor: often positive because tract is androgen dependent.

Why: ties it to male reproductive axis.
Negative: PSA, PAP, uroplakin, endothelial markers.

Why: separates from prostate, urinary tract, and vessels.

8. Typical Anatomic Correlate

Short, coiled ductules leaving the testis (rete testis → efferent ductules → head of epididymis).

Why: they are the “filtering and pumping” step between a high-volume testis and a concentrating epididymis.

Head (Caput)

1. Architecture

Tall pseudostratified columnar epithelium with very long stereocilia, plus basal cells.

Why: this is the segment that does the most fluid resorption so it needs the biggest apical surface.

All cells on a single basement membrane.

Why: preserves a single regenerative plane.

Lamina propria thin, closely applied to duct.

Why: short diffusion path for active transport.

2. Cytologic Features

Principal cells very tall, nuclei oval and at mid height.

Why: these cells are metabolically active and need space for organelles.

Apical stereocilia very long, irregular, non motile, actin based.

Why: they increase surface area for reabsorption without the energy cost of motility.

Basal cells small and triangular near the basement membrane.

Why: stem pool to repopulate principal cells.

3. Polarity and Junctions

Tight junctions near the apical part of principal cells.

Why: luminal composition must be tightly controlled so that sperm mature correctly.

Desmosomes laterally.

Why: duct undergoes contractile waves so the lining must not split.

4. Basement Membrane

Continuous basement membrane.

Why: needed for orderly regeneration and to maintain tubular shape.

5. Functional Correlation

Main function here is fluid resorption from testicular efferent ductules.

Why: sperm arriving from testis is in a relatively dilute fluid, which must be concentrated.

Also starts to modify the luminal environment for sperm maturation.

Why: early secretory products begin conditioning sperm.

6. Regeneration and Injury

Inflammation or obstruction can flatten the epithelium but basal cells can repopulate.

Why: BM is intact so repair is possible.

7. Biomarkers

Epithelial: pan CK+, CK7+.
Androgen receptor positive in principal cells.

Why: function is androgen dependent.
Actin positive stereocilia, FOXJ1 negative.

Why: proves these projections are not motile cilia.
Negative for PSA, PAP.

Why: separates from prostate.
Negative for endothelial markers.

8. Anatomic Note

Head of epididymis, close to testis, near efferent ductules.

Tail (Cauda) and Proximal Ductus Deferens

1. Architecture

Pseudostratified columnar epithelium becomes a bit lower, stereocilia can be shorter or sparser, basal cells still present.

Why: this segment is more for storage and propulsion than for massive resorption.

Lamina propria may be thicker, with more smooth muscle.

Why: tail and ductus need to move sperm during ejaculation.

2. Cytologic Features

Principal cells columnar, sometimes low columnar.

Why: secretion and absorption are less intense here.

Stereocilia fewer or shorter yet still actin based.

Why: less surface is needed for fluid handling.

Basal cells remain at BM.

Why: renewal compartment is still required.

3. Polarity and Junctions

Tight junctions present.

Why: luminal content still must be protected from blood derived immune cells.

Desmosomes and intercellular adhesion good.

Why: vigorous contractions should not detach the lining.

4. Basement Membrane

Continuous basement membrane.

Why: gives epithelium a fixed platform despite stronger muscularis.

5. Functional Correlation

Main role here is sperm storage and keeping sperm quiescent until ejaculation.

Why: sperm can be held here for days.

Epithelium contributes to luminal environment that keeps sperm viable.

Why: must prevent premature activation.

Proximal ductus adds muscular propulsion, epithelium mainly protects.

Why: mechanical transport is more important than absorption.

6. Regeneration and Injury

Obstruction or inflammation can cause epithelial flattening or atrophy.

Why: pressure and infection damage the lining.

If BM is intact, repair is possible.

Why: cells can crawl along it again.

7. Biomarkers

Epithelial: pan CK+, CK7+.
AR positive, often a bit weaker than in head.

Why: androgen still influences secretory tone.
Actin positive stereocilia, FOXJ1 negative.

Why: projections are still non motile.
Negative for PSA, PAP, uroplakin.

Why: separates from prostate and urinary tract.

8. Anatomic Note

Distal epididymal tail merging into the proximal part of the ductus deferens, the zone that is clinically relevant in obstruction and vasectomy.

Epididymis

Head (Caput)

Body (Corpus)

Tail (Cauda) and Proximal Ductus Deferens

Efferent Ductules (testis → epididymis) CILIATED EXCEPTION IN EPIDIDYMIS

Proximal Male Urethra and Ejaculatory Ducts

1. Architecture

Pseudostratified columnar or columnar to pseudostratified, often without cilia, sometimes with secretory cells.

Why: these ducts conduct viscous seminal fluid or urine, so they need a lining that can handle variable flow but does not necessarily need mucociliary clearance.

All cells on basement membrane, luminal cells taller.

Why: maintains a single repair plane.

2. Cytologic Features

Tall columnar to pseudostratified cells with apical secretory features.

Why: provides local lubrication and protection.

Basal cells small and dark at BM.

Why: reserve population.

May transition to stratified columnar or even urothelial segments.

Why: male urethra is a long mixed tube.

3. Polarity and Attachment

Tight junctions apically.

Why: protects underlying tissue from semen and urine.

Desmosomes laterally.

Why: urethra stretches.

4. Basement Membrane

Continuous BM over vascular connective tissue.

Why: urethra has abundant venous plexus, so epithelium needs a stable base.

5. Functional Correlation

Role: provide a smooth, protective, secretory lumen for mixed contents.

Why: semen and urine are chemically different and sometimes irritating.

6. Regeneration and Injury

Inflammation, infection or catheter trauma can cause areas to become stratified or squamous.

Why: chronic insult makes the body choose a tougher lining.

7. Biomarkers

Epithelial: pan CK+, CK7+, CK19 variable, EMA+.

Why: typical mucosal ductal pattern.
Basal cells: p63+, CK5/6+.

Why: shows reserve layer.
Androgen receptor: often positive.

Why: male tract epithelium is hormonally influenced.
GATA3 can be positive in segments close to urothelium.

Why: overlap with urothelial differentiation.
Negative: uroplakin in most of these non urothelial, pseudostratified segments.

Why: helps to separate from true urothelium.

8. Typical Anatomic Correlate

Prostatic and membranous portions that still show pseudostratified pattern, ejaculatory ducts entering the prostatic urethra.

Non-Ciliated

Proximal Male Urethra and Ejaculatory Ducts

Epididymis